Along with the development of technology for fabrication of solid-state image sensors, such as a charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) image sensor, electronic devices equipped with a small, lightweight lens assembly, such as mobile communication terminals, have already been commercialized and increasingly encroached on the market of compact digital cameras. As a lens assembly is mounted in a mobile communication terminal usually carried with a user, the user may easily use various functions including video call and augmented reality as well as image or video capturing.
Owing to the proliferation of lens assemblies in electronic devices and the development of optical technology, the lens assemblies may be miniaturized and have improved performance (for example, video quality). To improve the performance of a lens assembly, an automatic focusing function may be used. The automatic focusing function moves an image sensor or a lens positioned ahead of the image sensor along an optical axis according to a distance to an object, and thus enables acquisition of a clear image on an image forming surface of the image sensor.
To improve the performance of a lens assembly, an optical image stabilization (OIS) technique may also be used. According to the OIS technique, shaking of an object image caused by human vibrations such as hand tremors of a user is compensated for. The OIS is possible by detecting vibrations of an electronic device such as a camera through a plurality of angular velocity sensors mounted in the electronic device, and moving a lens or an image sensor according to the angular velocity and direction of the detected vibrations.
The automatic focusing function or the OIS technique may be implemented through linear movement of a lens (and/or a lens barrel) with respect to an image sensor or linear movement of the image sensor with respect to the lens. Even though a structure is installed to increase the performance of the lens assembly, there are limitations in compensating for tremors caused by rotational vibrations of the image sensor with respect to an object. For example, the automatic focusing function or the OIS technique compensates for shaking of an object image with linear movement corresponding to vibrations. However, since curved movement or rotational vibrations may occur during actual capturing, correction of tremors with linear movement has limitations in improving the quality of a captured image.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.